I. Field of the Invention
The present invention relates to electrical systems and, in particular, the present invention relates to an electromagnetic means for maintaining a rotating flywheel at a predetermined velocity.
II. Description of the Prior Art
Direct current or DC machines are used either as an electric motor fed by DC power supply or as a generator which produces a direct current. The motor and the generator are essentially identical in construction; that is, a DC machine may be used for either purpose. Generally, the DC machine comprises a stator which may have two magnetic poles for producing a magnetic field and a rotor usually called the armature in a DC machine which rotates between the poles. The stator poles are provided with windings through which the current flows. The armature may also have windings consisting of conductors (coils of wire) disposed in grooves formed in the armature core with the latter being generally composed of sheet steel laminations. The end of the armature core coils are each connected to one of the insulated copper segments of a commutator. The current for driving a motor is applied through brushes and the commutator, and at the same time part of the current is used to energize the field windings. The commutator is generally mounted on the armature shaft and rotates with it. When current is passed through the armature windings of a motor, the magnetic fields of the armature and stator strive to place themselves parallel to each other. As a result, the armature develops a torque (turning moment) about its shaft. The magnitude of the torque is proportional to the strength of the magnetic field and of the current. There are generally three types of motors. The first is known as the shunt motor wherein the field winding is connected and parallel with the armature and is, thus, energized by a current of constant voltage so that the magnetic field is constant. In such shunt motors when a load is applied the speed decreases, but not considerably. This type of motor has a fairly constant speed at all loads and is especially suitable for driving machine tools and the like. In the second type of motor known as the series motor, the field and armature windings are connected in series so that the strength of the field is dependent on the motor load and varies with the armature current. Such motors generally develop a high torque at starting and run at a speed depending on load. The third form of motor is known as the compound motor which has, in addition to the shunt field windings, a series winding which reinforces the field and gives a fairly high starting torque while retaining the speed limiting properties of the shunt winding.
If the armature winding of a DC generator is connected to continuous slip rings instead of to a segmented commutator, an alternating current (AC) is collected from these rings by the brushes. In this type of machine the armature winding in which the output current is generated is on the stator (the stationary frame in the machine) while the field system revolves on the rotor. The voltage produced by the AC generator depends on the strength of the excitation current, speed of rotation in a number of pairs of poles on the magnetic wheel. The frequency of the voltage is also directly dependent on the speed and the number of pole pairs. the aforementioned description of the AC and DC motors and generators is representative of the basic prior art principles; however, as will be seen hereinafter applicant's novel invention utilizes the simplicity of a DC motor but provides an alternating current input in time relation to the movement of a rotating armature to obtain a smooth continuous output.